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Published: 1958

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Irradiations were made on a number of uranium-plutonium alloy specimens made from both cast and extruded materials. The cast alloys included alloys of uranium with 3.7, 5.6, and 13.0 wt. % plutonium, and the extruded alloys included alloys of uranium with 9.5, 14.1, and 15.7 wt.% plutonium. One-half of the extruded specimens were given a heat treatment consisting of heating to 545 deg C and cooling to and holding at 500 deg C for one hour in an attempt to remove the preferred orientation that was anticipated from extrusion. The specimens were irradiated to burnups ranging up to 0.54 at. % with central temperatures ranging up to 490 deg C. The cast specimens were all found to have developed severe surface roughening as a result of the irradiation they received, presumably because of excessively large grain sizes present before irradiation. Identically fabricated unalloyed uranium specimens showed similar behavior. The as-extruded alloy specimens maintained good surface smoothness under irradiation, but showed elongations which were dependent on plutonium content. For example, in samples with 0.4 at.% burnup, a 14.1 wt.% plutonium alloy specimen elongated 96%, whereas an 18.7 wt. % plutonium alloy specimen elongated only 5.4%. The heat-treated extruded specimens did not elongate anisotropically, indicating that the heat treatment used was effective in randomizing the grain orientation. However, the heat-treated specimens developed excessive surface roughening, apparently because the heat treatment caused an undesirably large grain size. (auth).